Corrected glyphs for agnoster theme.

Running iTerm2 on OSX, I found that the glyphs were broken for the agnoster theme. The glyphs I've changed to seem to work fine for me, but dont work in Terminal. I would suggest someone test this on their machine, alternately, we could provide iTerm2 themes seperately.

EDIT: Correction, this actually works fine in Terminal, I forgot my Terminal wasn't using a patched font.